The use of drugs, such as bromouracil derivatives and certain electron affinic compounds, for enhancing the radiation sensitivity of malignant cells is a potentially useful technique in the treatment of cancer. The aim of this study is to determine the mechanism of the sensitizing effect. A combination of ESR-ENDOR spectroscopic and cryogenic techniques will be used to study the free radiation stages of the radiation damage process in the presence of these agents. NMR spectroscopic methods will be employed to study the later stages of the radiation process in which diamagnetic products are formed. BIBLIOGRAPHIC REFERENCE: "Radiation-Induced Oxidation and Reduction of Nitromethyluracil". H.C. Box, G. Potienko and E.E. Budzinski, J. Chem. Phys. 66, 342-346 (1977).